Phase shifters are known. Various systems require a relatively closely controlled phase for signals provided by such systems. For example, various transceiver systems need to control relative phase between two or more signals fairly closely and phase shifters are one way to facilitate this phase control.
One concern with variable or selectable phase shifters is typically a change in insertion loss occurs with a change in phase shift. This is undesirable and leads to complications such as a variable attenuator to offset such changes in insertion loss. Even if an attenuator exists in the relevant system for other reasons, that attenuator will need to be more complicated with more steps if it serves multiple or additional purposes.